Ionization dental system



Nov. 2, 1965 v. H. DlETz 3,215,139

IONIZATION DENTAL SYSTEM Original Filed May 22, 1961 v 2 Sheets-Sheet 1 Nov. 2, 1965 v. H. DlETz IONIZATION DENTAL SYSTEM Original Filed May 22, 1961 2 Sheets-Sheet 2 oFF United States Patent() 1o claims. (Cl. 12s-172.1)

This application is `a division of my application Serial No. 111,544, tiled May 22, 1961.

This invention relates to improvements in ionization treatment Aof individuals and in particular is concerned with a fluoride ionization treatment, which is termed hereinafter .as electroiiuoridizing for u-se in dental prophylaxis.

Fluoride treatment for prevention or reduction of dental caries has been the subject of widespread research. Such treatment is basically preventive in nature, and where ingestion of the uoride is contemplated very little eii'ect is had upon individuals having severe dental caries problems.

By means of this invention there has been provided a system for the treatment of individuals who have advanced Acases of dental caries. Particularly, i-t has been found that by the treatment of this invention rampant caries, dental lesions of the erosive type, and decay and decalcication can be beneficially treated. Essentially, this invention contemplates the provision of an electrode system in which a fluoride composition in an electrolyte carrier is contacted with the teeth of the individual. The electrode system is then energized and the fluoride is ionized to provide fluoride ions in a readily available form to be assimilated into the tooth structure.

In the system of treatment, readily ionizable lithium fluoride is incorporated into a matrix of sodium alginate. The sodium alginate in the mixture with lithium iluoride is in dry form, and when water is added it assumes the form of a gel-like nature with the water acting as an electrolyte for the ionization of the lithium iiuoride. The matrix is provided in an electrode mouthpiece tray which is fitted over the teeth. The electrode system is then connected to a source of electrical energy and the circuit is completed back to the individual by another electrode in contact with the body of the individual.

A control device is employed that may be used to regulate the current at a specified level of milliamperes to prevent injurious currents from being used. Further, `a timing device and automatic scale is provided so that the proper current level, combined with the time of treatment, may be provided.

The electrode employed for the use of the matrix composition of the lithium fluoride and the sodium alginate is specially formed so that there are no exposed electrically conductive parts that will engage the skin of the individual to cause shock or burn. The other electrode employed upon the body of the individual is also of a form to prevent shock or burn. This other electrode may be in the forrn of an adhesive bandage provided with an adhesive area whereby it may be readily placed upon the forehead or other substantially smooth surface of the individual and can be of a disposable nature. Still a further form may be in the shape of a salvia tube that can be readily placed in the mouth of the individual, or a simple wrist or handheld electrode may be used.

The system -o-f treatment is one that can be readily employed by the average dentist with a high degree of beneicial results without the necessity of complicated controls or other requirements. The simplicity of this system with the readily employable components makes the applicability of the system to a Wide range of individuals possible.

Further, this system is capable of treating, optimally, all surfaces of all teeth simultaneously. However, it appears preferable to treat one complete dental arch, upper or lower, at one time. As the average treatment of one arch is about fifteen minutes, it is simple to treat all exposed surfaces of all teeth Within a single appointment if desirable.

The features of applicants invention pointed out above are objects of the invention. yFurther objects will appear in the detailed description which follows and will be otherwise apparent to those skilled in the art.

For the purpose of illustration, there is .shown in the accompanying drawings a preferred embodiment of this invention. It is to be understood that these drawings are for the purpose of example only, however, and that the invention is not limited thereto.

In the drawings:

FIGURE 1 is a pictorial view showing an individual being treated with the dental treatment system of this invention;

FIGURE 2 is an enlarged plan view of an electrode mouthpiece tray that holds the lithium liuoride and lalginate composition;

FIGURE 3 is an enlarged view in section of the line 3 3 -of FIGURE 2 showing the structure of the mouthpiece;

FIGURE 4 is a top plan view of a disposable bandage type of electrode;

FIGURE 5 is a bottom plan view of the electrode;

FIGURE 6 is a view in section taken on the line 6-6 of FIGURE 4 showing the -construction of a modified electrode;

FIGURE 7 is a plan view of the modified electrode in the form of a salvia tube with the bottom portion being shown partly in section;

FIGURE 8 is an enlarged view in section taken on the line 8 8 showing perforation passages in the salvia tube and the construction of the tube;

FIGURE 9 is an enlarged view in section taken on the line 9 9 yof FIGURE 7 showing further details of construction;

FIGURE 10 is an enlarged view in axial section showing the curved end of the salvia tube and its structure;

FIGURE 11 is a view in elevation of an electrical control device employed in the treatment system of this invention; and

FIGURE 12 is a schematic wiring diagram of the control device.

The lithium iiuoride matrix composition employed in this invention preferably employes lithium fluoride in an amount from 5% up to about 35% of the dry sodium alginate. This mixture is in the form of a powder and when water is added in sufficient amounts gelation is caused. The mixing may take place in the mouthpiece electrode, or the mixture may be added to the electrode right after the water addition. Setting takes place in three or four minutes or so.

Lithium fluoride is the fluoride compound that is preferably used in this invention, although it is contemplated that other ionizable fluorides, such as calcium fluoride and similar relatively insoluble fluorides, could also be used without adversely affecting the gelation. However, it has been found that the lithium fluoride is particularly compatible with the sodium alginate and because of its relatively low solubility and yet its high degree of ionization capacity, it is preferred. It may, however, be supplemented by the use of up to about 0.75% of sodium fluoride based on the Weight of the alginate. The sodium fluoride, because of its ready solubility compared to the lithium iiuoride, provide a rapidly available source of sodium fluoride also acts to retard gelation somewhat and can be used to balance the speed of gelation, because of this fact.

Normally, gelation takes place when the water is added to form an impressionable material in the order of about three to four minutes. The setting time, however, can be reduced by the employment of about 0.25% to 0.50% of sodium chloride, as an accelerator, added to the lithium fluoride composition. The time period for gelation may be reduced to about two and one-halt` minutes by such addition. Also, the sodium chloride, as a readily soluble electrolyte, is of value in promoting the ionization of the fluoride in this system of treatment. Lastly, the sodium chloride acts as a balance to the use of sodium fluoride. Thus, it makes possible the use of up to about 0.75% of the sodium .fluoride based on the weight of the alginate, whereas, otherwise, only up to about 0.50% can be used.

As an actual example for the use of the mixture in the mouthpiece electrode, grams of the' sodium alginate may be employed. As much as three and one-half grams lithium fluoride, 50 mg. of NaCl and 75 mg. of NaF are then added to the alginate. The readily soluble NaF is an immediately available source of fluoride ions and, as

a retarder, balances the rate of gelation. Then water is added in sufficient quantities with mixing to form the gel. Setting occurs in two to three minutes.

The use of the sodium alginate as the gel forming material is quite desirable as it has a substantially neutral pH and is physiologically innocuous. At the time of mixturethe pH is about 7.8 and after each minute of set the pH is reduced about 0.1 to an average of 7.4. The alginate is a hydrocolloid and sets by gelation upon the addition of water without the requirement of heat. is contemplated that other vegetable gums may also be employed, such as gum tragacanth, agar agar, although the latter generates somewhat more heat in the gelation and is not quite so desirable upon this point.

In the lithium fluoride and alginate mix composition as described above, the sodium ion is believed to enhance the ionization. At least where sodium fluoride is added, the fluoride ion becomes available sooner. The additional use of sodium chloride for rapid setting and ionization promotion makes available the chloride ion which is in the treatment physiologically indifferent and is desired because it is very helpful for the electrolysis. Besides sodium chloride, sodium sulfate or nitrate may also be employed. Here again the sulfate and nitrate ions are also relatively physiologically indifferent and helpful in elec- 'trolysis.

Reference will now be had to the apparatus employed in the system of treatment of this invention. FIGURE 1 shows the apparatus vgenerally identified by the reference numeral 20. As there shown, it comprises a mouthpiece electrode 22, and which is used as a negative electrode, a positive electrode 24, and leads connecting these electrodes to a control unit 26. The controlunit provides a source of electrical energy and means for regulating it to the desired current and for a desired period of time.

The mouthpiece electrode is more particularly shown in FIGURES 2 and 3. As there shown, it is comprised of a body portion or a tray portion and a handle portion 32. The body portion 30 is made up of a perforated metallic member 34, which is in the form of a U or a horseshoe conforming to the either upper or lower arches of an individuals teeth. An upstanding rim 36 surrounds the peripheral area of the body portion to form a tray so that the electrode may belilled to a desired level with the matrix. Extending to one side of the body portion, and formed integrally therewith, is a flat metallic extension element 38. The free end is exposed and forms a .portion for an electrical clamp andhas an opening 40 lprovided for the insertion of an electrical lead screw, or

the like, if said is desired to be used.

An insulating covering 42 is formed on the bottom of top thereof into the interior as particularly shown in FIGURE 3. This insulated covering 42 extends over to the handle portion adjacent the body portion. The insulating covering insures that no metallic part will come into contact with the lips or `soft tissues of the mouth of the patient and thereby properly directs the ilow of fluoride ions to the external tooth structure and lcssens the possibility of burns or electrical shocks.

It will be noted that the bottom of the tray comprising the metal portion 34 is perforated and exposed. This makes better electrical contact possible between the lithium fluoride and sodium alginate matrix, and, by virtue of the perforations, better adhesion of the matrix into the tray is also insured. The internal beading 36 of the insulating material primarily assists in the retention of the set alginate mixture in the tray.

The saliva tube electrode 24 shown in FIGURE 1 is more particularly shown in FIGURES 7 through 10. As there shown, it comprises a metallic electrically conductive saliva tube 46, which has an opening 48 at one end. A number of perforations 50 are also provided adjacent this end. The opposite end of the metallic tube is connected to a saliva hose 52 that may be led to a convenient source of drainage. An electrical lead may be attached to the lower end of the metal saliva tube as shown in FIGURE 7. An insulating covering 56 extends over the free end of the saliva tube and into the shank of the tube. This covering extends adjacent the opening 48 and is provided further with perforations 57, which are in registry with the aforementioned perforations 50 of the metal tube. By providing these perforations, additional saliva tube passages for the saliva are made available.

A modified electrode 60 is shown in FIGURES 4 through 6 that may be used in place of the saliva tube electrode. As there shown, this electrode is in the form of a disposable bandage type of structure. It employs a fabric backing 62 over which is centrally placed a metallic foil 64 of somewhat similar area than the backing. Covering the metallic foil is a layer of porous and water absorbable fabric 66. This may be cotton, moleskin, or other water absorbable material. An electrical lead 68 may be soldered or otherwise electrically connected to the metallic foil and provides a source of electrical contact to the electrode.

For the purpose of adhesively securing the electrode to a smooth skin surface of the individual, an adhesive area 70 is provided around the peripheral border of the bottom of the fabric backing. This is most particularly shown in FIGURE 5.

The control device 26 is shown in FIGURES 11 and 12. As shown in FIGURE 11 the control device is incorporated in a housing 76 provided with a batte-ry selector lswitch 78 and a polarity reversal switch 80. An on-off switch 82 is employed to turn the current on or off. A flasher bulb 84 is also provided to indicate the operation of the device.

The control means for varying the current and the time period of current flow is provided by a potentiometer knob 85, which, in combination with an indicating scale `86, determines the proper setting which may be used as control device, a current meter comprising a milliampere Vscale and an indicating needle 91 are provided. The

scale is calibrated in milliamperes from zero to live, the

upper limit of the live milliamperes being the generally accepted limit applicable for treatment to individuals. In registry with the milliampere scale is a time period scale indicated by the reference numeral 92.

It will be particularly noted that the milliampere scale 90 and the time period scale 92 are in particular registry with one another. The milliampere scale reads clockwise from zero to five minutes, whole the time period scale reads counterclockwise. The time period scale is particularly graduated in order that when any milliampere reading is provided the needle will fall on the time period scale at a point to indicate a product of 30 milliampere minutes. This corresponds to the accepted Prinz formula for ionization treatment of individuals. Thus, for example, as shown in FIGURE l1, the indicating needle 91 registers 1.5 milliamperes on the current scale 90. The needle falls on the time period scale 92 at 20 minutes and the product of the time and the current will be 1.5 milliamperes times 20 minutes equalling 30 milliampere minutes. By this means once the current has been established the necessary time period to provide the 30 milliampere minutes can be directly read off the time period scale and the time period knob 88 may be turned to the proper position. Thus, it will be noted that in FIGURE 1l, to effect the proper combination of the current reading with time period scale, the knob 88 for the time period setting has been turned to the 20 minute position.

The control device 26 is provided with a pair of leads 94 and 96 which provide a source of electrical energy to the system. The leads 94 and 96 may be connected to l the previously described electrodes 22 and 24 as shown in FIGURE l, and, for the position shown and the particular position of the battery selector switch 78, the lead 94 is the negative lead while the lead 96 is the positive lead. It will be understood that instead of the batteries as a source of direct power, alternating current with a rectifier may be employed.

The schematic wiring diagram for the control device is shown in FIGURE 12. As there shown, the electrical energy source is shown in section 100 comprising two batteries 102 and 104, each battery being of 67.5 volts, as an example. Either battery may be thrown into the circuit by operation of the selector switch 78. The offon switch 82 is connected in series with the battery source. A conventional flasher circuit 106 is shown connected in parallel in the circuit so that the flasher bulb 84 flashes when the circuit is energized. The flasher circuit comprises a condenser 110 and a resistor 112 in parallel With the flasher bulb and a resistor 114 and condenser 116 in series. The entire circuit is connected in parallel to the main leads of the control device 94 and 96.

The potentiometer adjustment knob 88 is adapted to provide a variable current depending upon its adjustment with relation to a potentiometer resistance 118.

The milli-ammeter is shown generally indicated in the circuit as element 120 and a fuse 122 is provided for circuit protection and for protection to the individual. The time period adjustment control, comprising the adjustment knob 88 and the scale 89, is generally indicated by element 124, likewise connected to the circuit in series. The battery polarity reversal switch 80 is shown comprising a ganged switch for reversal of the leads 94 and 96 to opposite terminals of the battery Where battery polarity reversal is desired. Such battery polarity reversal may be desired for application of additional electrical dental or medical techniques to an individual apart from the fluoride treatment system of this invention.

Operation In the system of treatment of this invention the lithium fluoride and sodium alginate matrix is first prepared as previously described. Upon the addition of Water to the dry powder lithium fluoride and sodium alginate preparation with the suitable amounts of NaCl and NaF modifiers, and upon mixing, gel forms. This is effected in a rubber bowl. This mixture is then, in the viscous state, placed directly in the mouthpiece electrode tray 24.

The tray is then placed in the mouth of the individual with the upper teeth or lower teeth, as the case may be depending upon which is being treated, being impressed into the matrix immediately before setting, which occurs in the space of two to three minutes or so. The individual may hold the tray in place by grasping the handle. The mouthpiece tray 22 is the negative electrode and the positive electrode may be either the saliva tube electrode 24 or the bandage type of electrode 60. If the cloth and adhesive electrode 60 is employed it is preferably secured to the forehead of the individual, although an arm wrist or hand surface or other relatively smooth surface may be employed where desired.

Once the system has been connected, as shown in FIG- URE l, the potentiometer is turned to its most counterclockwise position to provide the highest resistance in the circuit and the lowest current possible for safety purposes. Then the on-off switch is turned to the on position. The potentiometer knob 85 is then turned toward the clockwise position to increase the current. This is accomplished slowly to a point where the increase in current causes just a very slight tingling sensation in the individual, which normally occurs at about two to three milliamperes and may, in exceptional instances, be as high as five or even less than two. After this tingling sensation is first recorded by the individual, the potentiometer knob is backed off to provide a reduction of about 0.5 milliampere for complete safety and comfort. Once the current setting has been established as set forth, the time period is read off the scale 92, and, as an example for the current reading of 1.5 milliamperes of FIGURE ll, the time period reading would be 20 minutes. The time period control knob 88 is then turned to the 20 minute position on the minute scale 89 of the control device. The timer then provides an automatic 20 minute treatment after which it breaks the circuit. This establishes a milliampere and time in minutes product of 30 milliampere minutes which is the established rating provided under the accepted Prinz formula.

The treatment aforementioned provides for a high level of fluoride ionization for the electrofluoridizing treatment of rampant caries and other conditions of the teeth that are benefited by fluoride treatment. It is to be understood that also the system may be used for preventive treatment and any level of fluoride ionization may be provided by increasing or decreasing the fluoride concentration in the sodium alginate mix.

It will also be understood that the apparatus of this invention may be employed for any medical ionization or electnolysis treatment of individuals with or without the fluoride treatment. Thus, by the provision of the electrode, automatic timing upon a set current control can be established. Such further applications may be used by reversing the polarity to prevent adverse gum conditions, recessive demineralization of the jaw bone, and atrophy, and for lother accepted medical and dental treatments.

Various changes and minor alterations may be made in the system of this invention as will be readily apparent to those skilled in the art. Such changes and alterations are within the scope Iand teaching of this invention as defined by the claims appended hereto.

What is claimed is:

1. An electrical control device for use in ionization treatment of individuals, said control device having an adjustable source of electrical current, means for varying said electrical current, means for connecting said device to a pair of electrodes, and means for setting the control device to provide an electrical current for a variable period of time.

2. An electrical control device for use in ionization treatment of individuals, said control device having an adjustable source of electrical current, means for varying said electrical current, means for connecting said device to a pair of electrodes, and means for setting the control device to pr-ovide an electrical :current for a variable period of time, saidcontrol device being further provided with an electrical current meter scale in registry with a variable time period scale whereby an indicating meter scale pointer registers with the time period scale to indicate the time period necessary to provide the current to fulfill the Prinz formula of 30 milliampere minutes.

3. An electrical control device vfior use in ionization treatment of individuals, said control device having an adju-stable source of electrical current, means for varying said electrical current, means for connecting said device to a pair of electrodes, and means for setting the control device to provide an electrical current for a variable period of time, said control device being further provided with an electrical current meter scale in registry with a variable time period scale whereby an indicating meter scale pointer registers with the timel period scale to indicate the time period necessary to provide the current to fulfill the Prinz formula of 3() milliampere minutes, said control device being further provided With a plurality of batteries and means for switching a selected battery into and out of operation.

4 An electrical control device for use in ionization treatmentol;` individuals, said control device having an adjustable source of electrical current, means for varying said electrical current, means for connecting said device to a pair of electrodes, and means for setting the control device to provide an electrical current for la variable period of time, said control device being further provided with an electrical current meter scale in registry with a variable time period scale whereby an indicating meter scale pointer registers with the time period scale to indicate the time period necessary to provide the current to fulll the Prinz formula tof 30 milliampere minutes, and switching means for reversing the polarity of the electrical current. y 5. An electrical control device for use in ionization treatment of individuals, said control device having an adjustable source of electrical current, means for varying said electrical current, means for connecting said device to a pair of electnodes, and means for setting the control device to provide an electrical current for a variable period of time, said control device being further provided with an electrical current meter scale in registry with a variable time period scale whereby an indicating meter scale ponter registers with the time period scale to indicate the time period necessary to provide the current to fulll the Prinz formula of 30 milliampere minutes, and a flashing circuit with a flashing bulb energized when the control device is energized.

6. An electrical control device for use in ionization treatment of individuals, said control device having an adjustable source of electrical current, means for varying said electrical current, means for connecting said device to a pair of electrodes, and means for setting the control device to provide an electrical current for a variable period of time, said control device being further provided with an electrical current meter scale in registry with a variable time period scale whereby an indicating meter scale pointer registers with the time period scale to indicate the time period necessary to provide the current to fulfill the Prinz formula of 30 milliampere minutes, .said control device being further provided with a plurality of batteries and means for switching a selected battery into and out of operation, and switching means for reversing the polarity of the electrical current, and a llashing circuit with a flashing bulb energized when the control device is energized.

7. A system for electrotluoridizing the teeth of an individual which comprises establishing an electrical mouth- 'piece grid electrode holding an impressionable matrix containing an ionizable -fluoride engageable by the teeth, said electrode being formed in a substantially flat U-shaped v`body and having a handle joining said body at a medial portion, said body and handle being formed from a rigid electrically conductive material, an insulated rim extending :around said body an-d an insulated covering for said handle adjacent the joinder of the handle with said body and extending along said handle to a point near a free end thereof while leaving the end exposed for an electrical connection, `a second electrode engageable with the body of the individual said electrode comprising a fabric backing, an electrically conductive foil emplaced over a portion of said backing, a water permeable cover engaging the fabric backing overlying said foil and an Aadhesive area bordering said cover for adhesively securing said electrode to a -body surface of said individual and electrical energizing means externally connecting said electrodes.

8. A system for electrolluoridizing the teeth of an individual which comprises establishing an electrical mouthpiece grid electrode holding an impressionable matrix containing an ionizable fluoride engageable by the teeth, said electrode being formed in a substantially at U-shaped body and having a handle joining said body at a medial portion, said body and Ahandle being formed from a rigid electrically conductive material, an insulated rim extending around said body and an insulated covering for said handle adjacent the joinder of the handle with said body and extending along said handle to a point near a free end thereof while leaving the end exposed for an electrical connection, a second electrode engageable with the 'body of the individual, said electrode comprising a fabric backing, an electrically conductive foil emplaced over a portion of said backing, a water permeable cover engaging the fabric backing overlying said foil and an adhesive area bordering said cover for adhesively securing said electrode to a 'body surface of said individual and electrical energizing means externally connecting said electrodes, said means comprising a control device having an adjustable source of electrical current, means for varying said electrical current, means for connecting said device to said aforementioned electrodes, and means for setting the control device to provide an electrical current for a variable period of time, said control device being further provided with an electrical current meter scale in registry with a variable time period scale whereby an indicating meter scale pointer registers with the time period scale to indicate the time period necessary to provide the current to fuliill the Prinz formula of 30 milliampere minutes.

9. A system of electrotluoridizing the teeth of an individual which comprises establishing an electrical mouthpiece grid electrode holding an impressionable matrix containing an ionizable fluoride engageable by the teeth, said matrix comprising an impressionable gelable matrix and fluoride ionization upon the addition of water sulhcient to promote gelation and fluoride ionization and comprising sodium alginate and an ionizable fluoride compound, said electrode being formed in a substantially ilat U-shaped body and having a handle joining said body at a medial portion, said body and handle being formed from a rigid electrically conductive material, an insulated rim extending around said body and an insulated covering for said handle adjacent the joinder of the handle with said body and extending along said handle to a point near a free end thereof while leaving the end expose-d for an electrical connection, a second electrode engageable with the body of the individual, said electrode comprising a fabric backing, an electrically conductive foil emplaced over ya portion of said backing, a water permeable cover engaging the fabric backing overlying said foil and an adhesive area bordering said cover for adhesively securing rsaid electrode to a body surface of said individual and electrical energizing means externally connecting said electrodes, said means comprising a control device having an adjustable source of electrical current, means for varying said electrical current, means for connecting said device to said aforementioned electrodes, and means for setting the control device to provide an electrical current for a variable period of time.

10. A systemof electroiluoridizing the teeth of an individual which comprises establishing an electrical mouthpiece grid electrode holding an `impressionable matrix containing `an ionizable uoride engageable by the teeth, said matrix comprising an impressionable gelable matrix and fluoride ionization upon the addition of water sufcient to promote gelation and uoride ionization and comprising sodium alginate and an ionizable fluoride compound, said electrode being formed in a substantially at U- shaped body and having a handle joining said body at a medial portion, said body and handle being formed from a rigid electrically conductive material, an insulated rim extending around said body and an insulated covering for said handle adjacent the joinder of the handle with said body and extending along said handle to a point near a free end thereof While leaving the end exposed for an electrical connection, a second electrode engageable with the body of the individual, said electrode comprising a fabric backing, an electrically conductive foil emplaced over a portion of said backing, a water permeable cover engaging the fabric backing overlying said foil and an adhesive area bordering said cover for adhesively securing said electrode to a body surface of said individual and electrical energizing means externally connecting said electrodes, said means comprising a control device having an adjustable source of electrical current, means for varying said electrical current, means for connecting said 4device to said Iaforementioned electrodes, and means for setting the control device to provide an electrical current for a variable period of time, said control device being further provided with an electrical current meter scale in registry with a variable time period scale whereby an indicating meter scale pointer registers with the time period scale to indicate the time period necessary to provide the current to fulll the Prinz formula of 30 millampere minutes.

No references cited.

ADELE M. EAGER, Primary Examiner. 

3. AN ELECTRICAL CONTROL DEVICE FOR USE IN IONIZATION TREATMENT OF INDIVIDUALS, SAID CONTROL DEVICE HAVING AN ADJUSTABLE SOURCE OF ELECTRICAL CURRENT, MEANS FOR VARYING SAID ELECTRICAL CURRENT, MEANS FOR CONNECTING SAID DEVICE TO A PAIR OF ELECTRODES, AND MEANS FOR SETTING THE CONTROL DEVICE TO PROVIDE AN ELECTRICAL CURRENT FOR A VARIABLE PERIOD OF TIME, SAID CONTROL DEVICE BEING FURTHER PROVIDED WITH AN ELECTRICAL CURRENT METER SCALE IN REGISTRY WITH A VARIABLE TIME PERIOD SCALE WHEREBY AN INDICATING METER SCALE POINTER REGISTERS WITH THE TIME PERIOD SCALE TO INDICATE THE TIME PERIOD NECESSARY TO PROVIDE THE CURRENT TO FULFILL THE PRINZ FORMULA OF 30 MILLIAMPERE MINUTES, SAID CONTROL DEVICE BEING FURTHER PROVIDED WITH A PLURALITY OF BATTERIES AND MEANS FOR SWITCHING A SELECTED BATTERY INTO AND OUT OF OPERATION. 